You can have the best schools in the world but if there are problems getting the children to them they are not going to be effective

Audit Commission's Greg Birdseye

It outlines concerns about poor quality vehicles, rude drives and badly-trained drivers, vandalism and bullying by other pupils.

The report also found that some authorities are even registering buses from Ireland as parents cannot understand the ages of the buses through the number plate.

It also says drivers and carers employed on the buses are not being screened properly and highlights problems of abuse.

Pat Harries, who has been heading the nationwide Busk campaign for nine years, said she welcomed the Audit Commission research.

She said it was now up to local education authorities to discharge their "legal duty of care" and provide better school transport.

"Safety does cost money," said Mrs Harries. "How many local education authorities are discharging there legal duty of care?"

Associate director of the Audit Commission Greg Birsdeye said their research had found spending on schools was considered more important than spending on school transport.

Pat Harries from school bus safety campaign Busk

"You can have the best schools in the world but if there are problems getting the children to them they are not going to be effective," he said.

"We are trying to think of ways of improving the service for them and to save the worries of parents themselves," he said.

One priority was to provide proper screening for bus drivers and for escorts who accompany some services.

"Some councils do put escorts on the buses to monitor pupils' behavious and to stamp down on bullying."

Mrs Harries said Busk has identified cases of abuse on school buses in south Wales.

"We are getting these complaints too often," she said.

It was up to parents to get confirmation from education authorities that a bus driver had been properly screened, she said.